Laminated product



Patented Oct. 29, 1940 2,219,684 7 LAMINATED PRODUCT Eric -WilliamReginald Oswald Gib Fawcett, Walton-upon-Thames, son, Northwich,Cheshire,

and Michael Willcox- Perrin, London, England, assignors to ImperialChemical Industries Limited, a corporation of Great Britain Drawing.Application March 2, 1939, Serial N0. 259,444. In

4 Claims.

our copending application- 722, filed February 2,

Serial Number 123,- 1937, which describes new ethylene polymers andtheir use as adhesives in the preparation of safety gla nated articles.

An object of this invention ss and other lamiis to provide a new andimproved type of laminated glass in which the laminae are united througha film or layer of great strength and durability. A still further objectis to provide methods for making laminated glass wherein the interlayercomprises a polymer of the type described tioned copending application.appear hereinafter.

These objects are accomplished by uniting two or more laminae by meansof a synthetic linear polymer in'the above-men- Other objects will alayer comprising which is produced in accordance with the methoddescribed in our aforementioned Patent ,2,153,553.

copending application or in U. S.

More particularly the invention comprises laminated glass composed oftwo sheets of glass having layer of the ethylene polymer as the solebonding agent and therebetween a film or which may be used as theinterlayer.

The solid polymers of ethylene used in the practice of this inventionare, prepared by a process which consists in subjecting ethylene to apressure in excess of 500 atmospheres under controlled elevatedtemperature conditions. This procedure results molecular Weight inpolymers of ethylene, the of which varies depending particularly uponthe pressure employed. By using pressures of more than 1000 atmospheres,solid polymers are formed and under these conditions the polymerizationreaction takes place, requiring several hours for completion.

mers may also be made (in a process described in These polyccordancewith the the copending application of Paton, Perrin and Williams, SerialNumber 157,810) by including in the ethylene a small quantity of oxygenwhich may be as little as 0.01% but preferably atmospheres and 190 areat least 500 atmospheres to 0.10% at 1500 to 210 C. The pressures andpreferably ,at

least 1000 atmospheres and below 3000 atmospheres. and 400 Thetemperatures are between 100 C. and more particularly from 150 C.

to 250 C. Thus, as a specific instance of obtaining the solid polymers,ethylene containing 0.05% oxygen is compressed in a steel bomb to atotal pressure of 1500 rapidly to 210 C., whereup atmospheres and heateda ry udden Great Britain February 4,

change in pressure followed by a slow drop in pressure is observed.After five hours heating at 210 C. the pressure is released and theproduct cooled. Under these conditions an yield of the solid polymer,based on the ethylene used, is obtained.

The ethylene polymers obtained as outlined above melt within or abovethe range of about to about C., have an average molecu-,- lar weight inexcess of 6000, are essentially saturated products corresponding incompositions substantially to (CH2), and when subjected to X-raydiffraction analysis show a crystalline structure. These polymers aresoluble in xylene at its boiling point, are unaffected by prolongedcontact with air at ordinary temperatures, and

' are characterized by the formed into films and filaments which yieldoriented products on'application of stress herein referred to as colddrawing. The oriented products furnish fiber difiraction patterns onexamination with X-rays and exhibit birefringence and parallelextinction when observed under crossed Nicol prisms.

The present invention consists in the application of the above-mentionedsolid polymers of ethylene in the preparation of laminated glass. It hasbeen found that solid polymers of ethylene having molecular weights inexcess of 10,000 can be made to form a satisfactory bond with glass, andthat the laminated articles so formed are substantially unaffected bychanges in temperature and humidity which such articles encounter inservice. Furthermore, the laminated glass is very good in resistance tothe commonly applied break and crush tests, and sensitive to widevariations in temperature. In other words, it is shatter-proof.Depending on the use to which the laminated article is to be put, theinterlayer may bra transparent, translucent, or opaque.

The-polymers mentioned above possess to an unusual degree the propertiesessential to the fact that they can be in this respect is not productionof a successful laminated or safety indicated, films, filaments and thelike prepared from the solid polymers of ethylene are furthercharacterized by the fact that they yield oriented products on colddrawing; in general, cold drawing improves the toughness, elasticity,and utilthe molten polymers. Fjilms prepared in this manner aregenerally translucent unless theyare cooled by rapid chilling, e. g., byextruding the polymer in sheet form into a suitable quenching liquidsuch as water. This rapid chilling or tempering of the hot films alsoleads to a tougher product. Films can be prepared by fiowing solutionsor emulsions of the solid polymers of ethylene on a suitable surface,as, for example, glass, and evaporating the solvent or by regeneratingthe film or sheet by extrusion into a suitable coagulating bath. Filmsobtained by these methods are also generally translucent, but they maybe made transparent by rapid chilling of the hot films as above stated.

The laminated articles of this invention can be prepared in a number ofWays. A convenient method consists in placing a layer or sheet of thesolid polymer of ethylene between two plates of glass and then pressingthe plates together under the influence of heat and pressure. Althoughthe thickness of the layer may be varied within wide limits dependingupon the type of product desired, for most purposes layers of 0.015 to0.050 inch thickness are'most desirable. The temperatures employed forthis purpose should preferably be below the melting point of the polymerif transparent laminations are desired. After adhesion has beeneifected, the article is allowed to cool to room temperature. Still an-40 other method consists in flowing a solution of the solid polymer ofethylene on the glass plate,

evaporating the solvent or at least the major portion thereof, and thenapplying the other plate of glass. or a solution, polymer in the form ofa powder may be used. The preferred method of efi'ecting laminationconsists in applying a suitable adhesive to both sheets of glass,interposing there- 50 between a preformed sheet of polymer, andcombining the two sheets of glass by means of heat and pressure.

The following examples in which the parts are by weight illustrate theinvention more specifi- 'cally:

Example! Five-inch by five-inch plates of glass were sprayed withadhesive A, hereinafter described, and allowed to dry for 15 minutes atroom tem- 0 perature. A coating of a toluene solution of an isobutylenepolymer having a molecular weight of about 10,000 was sprayed over thetreated glass and allowed to dry 4 hours at C. At the end of this time asheet of an ethylene polymer having a thickness of approximately 0.02inch and a molecular weight of about 18,000 was interposed between-twosheets of glass prepared as described above and the assembly heated toabout 105 C. under a pressure of about 4 lbs. per sq. in. in a platenpress.

in the press just long enough to melt the plastic. The assembly was thenremoved from the press and allowed to cool in air. Theresultant'laminated glass shows shatterproofness not only at- 50 C., butalso at 18 C.

The most useful solid poly- Instead of using a preformed mm The assemblywas kept Example II A uniform layer of approximately 0.02 inch thicknessmade from a polymer of ethylene having a molecular weight of about24,000 was placed on a clean plate. and the assembly heated to about C.-Another warm glass plate was then placed on the first plate andpressure was applied so that the ethylene poiymer formed an adherentinterlayer of uniform thickness, and the sandwich allowed to cool toroom temperature. The section of laminated glass thus formed wastransparent. When the laminated article was struck a sharp blow, anumber of radial cracks were formed but the section remained in onepiece and still had considerable strength.

Example III A tetrachloroethylene solution of an ethylene polymer havinga molecular weight of about 30,000 was poured onto an amalgamated tinplate and the solvent removed by evaporation on a steam heated plate.After most of the solvent had been removed, the plate was cooled and thesheeting stripped. A film was obtained 01' about 0.03 inch in thickness.Pieces of this sheet were then placed on thin tin plate sheeting andheated in an oven until, the material melted and all traces of solventwere removed. The sheets were then quenched rapidly in cold water. Thefilms were then cold rolled to about 0.020 inch in thickness.

Pieces of five-inch by five-inch plate glass were sprayed with adhesiveA described in Example I and allowed to dry 15 minutes at roomtemperature. The coated glass was then sprayed with a toluene solutionof an isobutylene polymer having a molecular weight of about 10,000, andthe treatedglass allowed to dry for 4 hours at 45 C. At the end of thistime the sheet of the ethylene polymer prepared as described above wasassembled between the treated glass sheets and the composite heated at80 C. under a pressure of 50 lbs. per sq. in. The resulting laminatedglass was shatterproof at 50 and at 18 C.

(7., room temperature,

Example IV Example V Two panes of window glass 2" x 5' x 54;" wereheatedin an ovenat C. Strips of an ethylene polymer (molecular weightabout 25,000)

0.20 inch by 0.03 inch thick were applied around the edge of one of thepanes and allowed to melt so as to form a continuous border of ethylenepolymer around the glass. The other glass pane was then superimposed onthe first, the assembly gently pressed, and then allowed to cool to roomtemperature. A clear composite glass consisting place of adhesive Atheir low densitymakes it possible to use thinnerof two glass panes,0.025 inch apart and separated by an air-tight, continuous film ofethylene polymer was obtained.

' Example VI To a hot glass pane 2" x5 x A,? was applied a border ofethylene polymer having a molecular weight of about 25,000 by layingaround the edge of the glass a border of the aforementioned ethylenepolymer in the form of strips 0.20 inch wide and 0.03 inch thick. Thepane was allowed to cool to room temperature, the ethylene polymer edgetreated with atoluene solution of an isobutylene' polymer'having amolecular weight of about 14,000, and the solvent allowed to evaporateat room temperature. A composite was prepared by placing over thetreated glass another glass and applying pressure in order to cause theethylene polymer-polyisobutylene film to form an adherent layer betweenthe two glass sheets. The double pane thus obtained was transparent andair-tight.

The foregoing examples are not to be considered as limitative but asillustrative of the products of this invention and methods for theirpreparation.

Gelatin or plasticized casein may be used in used in Examples I and III.

The film or interlayer used in the preparation of the laminated glassarticles of this invention need not. necessarily consist only ofethylene polymer. It is frequently desirable to use a softening orplasticizing agent in conjunction with the ethylene polymer. As anexample of a suitable plasticizing agent for this purpose may bementioned paraffin wax.

This invention provides a simple method for the preparation of laminatedglass articles of great'utility. Since the ethylene polymer films havesatisfactory bonding qualities, laminated glasses prepared therewith arecharacterized by strength and'durability. The good strength of theethylene polymer interlayers, coupled within making burglar-proof glass.

glass and lighter interlayers than is possible in the case of plasticmaterials previously described for this purpose. This is not only aneconomic advantage but also an advantage in utility since it makes itpossible to prepare laminated articles of less weight.

cause of their good strength and non-shattering properties are useful insafety glass in motor vehicles, airplanes, etc. The invention is alsouseful Another important' application of this invention is in thepreparation of double window glass.

As many apparently widely merits of this invention may be made withoutdeparting from the spirit and scope thereof, it is to be understood thatwe do not limit ourselves to the specific embodiments thereof except asdefined in the appended claims.

We claim:

l. A laminated article comprising two sheets of glass havingtherebetween a film of a solid polymer of ethylene which melts attemperatures above 100 C. r

2. A laminated article comprising two sheets of glass havingtherebetween a film of a sold polymer of ethylene which melts attemperatures above 100" C., and which has a molecular weight of at least6,000. I

3. A laminated article comprising two sheets of glass havingtherebetween a mer of ethylene capable of being drawn into fibers whichupon X-ray examination show orientation along the fiber axis.

4. A laminated article comprising two sheets of glass havingtherebetween a filmof a solid polymer of ethylene which is solid atnormal temperature, which corresponds in composition to (CH2); and whichby X-ray difiraction analysis shows a crystalline structure.

ERI WILLIAM FAWCETT. REGINALD OSWALD GIBSON. MICHAEL WILLCOX PERRIN.

different embodi- Theproducts of this invention befilm of a solid polyv

